The present application claims priority to Japanese patent application No. 2001-150435 of Takimoto et al., filed May 21, 2001, and Japanese patent application No. 2001-150448 of Takimoto et al., filed May 21, 2001, and the entirety of each is hereby incorporated into the present application by reference.
The present invention relates to a knee protecting airbag device which is provided with an airbag capable of protecting the knees of the passenger or driver in the front seats. The airbag extends and expands from a folded state when it is fed with an inflating gas.
In the prior art, a device for protecting the knees of a driver or a passenger has been disclosed in Unexamined Published Japanese Patent Application No. 80797/1996 or No. 315894/1998.
The airbag device of No. 80797/1996 is arranged at a portion on the lower side of a lower cover of a dashboard. This airbag device is provided with an airbag for protecting the driver from the ankles to the knees. When the airbag device is activated, the airbag protrudes obliquely upward from a lower position by extending and expanding.
The airbag device of No. 315894/1998 is arranged near a column cover below the steering wheel. This airbag device is provided with an extensible and expandable airbag. This airbag extends and expands to protect the area from the lower portions of the knees to the vicinity of the toes of the driver.
However, such knee protecting airbag devices have room for improvement with regard to efficient expansion with the passage of time from the start to the completion of the extension and expansion of the airbag, to protect the knees of a passenger such as the driver.
In view of this, an object of the present invention is to provide a knee protecting airbag device that can properly protect the knees of a passenger or driver in the front seat by extending and expanding the airbag efficiently throughout the extension and expansion of the airbag.
The vertical, transverse and longitudinal directions correspond to the vertical, transverse and longitudinal directions of the vehicle.
The word xe2x80x9cpassengerxe2x80x9d is used to refer to either a driver or a person in the passenger seat. That is, the word xe2x80x9cpassengerxe2x80x9d includes the driver.
In order to achieve the above-specified object, there is provided a knee protecting airbag device comprising an airbag for inflating, when fed with an inflating gas, to protect the knees of a passenger, and a housing portion for housing the airbag when folded. The housing portion is arranged on the lower side of a member on the vehicle body and in front of the knees of the seated passenger. The housing portion includes an opening for permitting the airbag to protrude toward the rear of the vehicle. The airbag is arranged in front of the knees of the passenger to extend and expand when fed with the inflating gas, out from the housing portion toward the vehicle rear. The airbag includes a lower expansion portion and an upper expansion portion. The lower expansion portion is in an upstream part of the flow of inflating gas and protrudes from the opening of the housing portion toward the rear, when fed with the inflating gas, to cover the front sides of the knees. The upper expansion portion is in a downstream part of the flow of inflating gas and protrudes upward from the lower expansion portion along the rear side of a member attached to the vehicle body to cover the periphery of the airbag opening and at least the portion above the airbag opening.
Just after the knee protecting airbag device of the invention is activated, the vehicle completes the front collision, and the knees of the passenger move forward relative to the vehicle. Just after the action of the airbag device, however, the lower expansion portion is located in the upstream part of the flow of the inflating gas and expands prior to the upper expansion portion, while protruding to the rear from the airbag opening. Therefore, the knees of the passenger can be properly protected by the lower expansion portion even if the knees move forward relative to the vehicle.
After the initial stage of the extension and expansion of the airbag, the knees of the passenger are bent to rise if the passenger moves relative to the vehicle while the feet of the passenger remain on the floor panel. In other words, the knees move upward to the rear side of a member attached to the vehicle body. This state takes place whether the knees are in or out of contact with the airbag. At this time, the airbag has already passed through the initial stage of the extension and expansion, and the upper expansion portion, which is in the downstream side of the inflating gas, has extended upward from the lower expansion portion along the rear side of a member attached to the vehicle body and has expanded to cover the periphery of the airbag opening and at least the portion above the airbag opening. Therefore, the upper expansion portion protects the upwardly moving knees. In other words, the knees can be protected against hard members such as the key cylinder by the upper expansion portion of the airbag even if the hard members are arranged in front of the upper expansion portion.
The upper expansion portion may start its expansion either after or before the expansion of the lower expansion portion is completed.
In the knee protecting airbag device according to the present invention, the expansions of the lower expansion portion and the upper expansion portion are completed to cover the position of the moving knees of the passenger. In other words, the airbag device of the invention adjusts the expansion mode of the airbag according to the time lapse from the start to the completion of the extension and expansion. In the airbag device of the invention, the airbag is not extended and expanded to provide a large protection area from the beginning of the expansion. Therefore, the airbag device can protect the two knees of the passenger properly without using a high-output inflator or an airbag having a large volume.
In the knee protecting airbag device according to the invention, therefore, the knees of the passenger can be properly protected by extending and expanding the airbag efficiently as the time elapses from the start to the completion of the extension and expansion of the airbag.
It is desired that the airbag is provided with a tether arranged in the interior of the airbag for connecting the vehicle and the passenger side (front and rear) walls of the airbag to regulate the thickness of the airbag when the lower expansion portion is extending and expanding. With this construction, the distance (or the thickness of the lower expansion portion) between the front wall and the rear wall of the airbag is regulated during expansion. In other words, the airbag feeds the inflating gas to the upper expansion portion without filling the lower expansion portion unnecessarily. Therefore, the airbag can promote the completion of expansion of the upper expansion portion. At the extending and expanding time of the lower expansion portion, it is of course necessary that the lower expansion portion is restrained from becoming excessively thick. Therefore, the lower expansion portion is smoothly arranged at a predetermined position even if the space between the front of the passenger compartment and the knees of the passenger is narrow.
It is desired that a flow-directing cloth is arranged in the airbag for guiding the inflating gas from the lower expansion portion to the upper expansion portion. With this construction, the inflating gas is directed from the lower expansion portion to the upper expansion portion by the flow-directing cloth, and the upper expansion portion easily protrudes upward from the lower expansion portion along the rear face of the member attached to the vehicle body while airbag protrusion directly out toward the rear is limited. As a result, the upper expansion portion is smoothly arranged between the knees of the passenger and the rear face of the vehicle side member.
In this case, the protrusion of the upper expansion portion to the rear can be further limited if the flow-directing cloth is arranged to guide the inflating gas upward along the rear face of the vehicle side member.
When the inflator is arranged in the lower expansion portion of the airbag, and the tethers connecting the front and rear airbag walls are arranged above and below the inflator, the flow-directing cloth may be formed into a sheet shape and may be supported by the tethers.
The airbag may have a cushioning pad attached to the outer surface of the rear wall in the lower expansion portion. This pad is made substantially flush with the peripheral edge of the protruding opening when the airbag is housed in the housing portion to clog the protruding opening, and moves when the airbag is extending and expanding to the rear of the vehicle as the lower expansion portion protrudes, so that it is arranged in front of the knees. With this construction, before the activation of the airbag device, the pad can close the protruding opening to improve the design of the peripheral edge of the protruding opening. When the airbag is extending and expanding, the cushioning pad moves to the rear as the lower expansion portion protrudes and is positioned in front of the knees. Therefore, the pad can protect the knees properly even if the knees move forward relative to the vehicle. The upper expansion portion expands and is arranged over the pad. Therefore, the upper expansion portion can protect the knees against hard members such as the key cylinder, even if the knees move upward where hard members on the rear side of the vehicle side member are located.
When the airbag includes a wall portion on the front side upon completion of the extension and expansion, and a wall portion on the rear side, opposite to the front side, upon completion of the extension and expansion, it is desired that the airbag is folded through a step of rolling the upper edge toward the front side wall. With this construction, at the time of unfolding the portions that were folded by rolling, the upper edge side of the airbag extends and expands along the rear face of the member attached to the vehicle while being unrolled, and the extension and expansion are then completed. At this time, the airbag is unfolded while coming as close to the rear side of the member attached to the vehicle as possible. Therefore, extension and expansion of the airbag toward the knees of the passenger is limited. The airbag can smoothly extend while being unrolled, even if it comes into contact with the knees of the passenger.
It is natural that the airbag need not be rolled, as described above. For example, the airbag may be folded in a cactus folding, such that the outer peripheral edge is folded within the airbag so that it may be housed in the housing portion.
The airbag may be constructed to extend further to the right or left when expansion is completed so that it can cover a hard member arranged on an instrument panel upon completion of the extension and expansion.
On the other hand, the airbag may be constructed such that its upper end portion upon completion of the extension and expansion has a smaller transverse size than the lower end portion. This construction may fail to cover the hard members arranged in the instrument panel. However, the airbag is provided with the upper expansion portion for covering the area above the airbag opening at the rear side of the member attached to the vehicle. Therefore, the upper expansion portion can protect the knees against the hard members near the portion of the rear side of the member attached to the vehicle that is closer to the passenger. Moreover, this airbag is reduced in total volume through narrowing the airbag at the left and right sides of the upper end portion. Therefore, this airbag has a shortened time period from the start to the completion of its expansion.
The airbag may be manufactured either by sewing the wall portions flat against each other or by sewing pieces which have been cut to match the three-dimensional expanded shape.
Still moreover, it is desired that at the initial stage of the extension and expansion of the airbag, the lower expansion portion protrudes to the rear from the airbag opening of the housing portion, and extends and expands transversely to cover the left and right peripheral edges of the airbag opening. With this construction, the airbag widely extends and expands so leftward and rightward that the lower expansion portion may cover the left and right peripheral edges of the protruding opening at the initial stage of the extension and expansion. Just after the action of the knee protecting airbag device, more specifically, the vehicle completes the front collision so that the knees of the passenger move forward relative to the vehicle. If the lower expansion portion extends and expands widely leftward and rightward from the peripheral edge of the protruding opening, it can protect the knees of the passenger properly even if the knees move a great deal leftward or rightward by the braking operation.
Means for extending and expanding the lower expansion portion transversely can be constructed of a gas flow guide member arranged in the airbag for guiding the inflating gas in the lower expansion portion to two transverse sides.
When a tether is arranged in the airbag for connecting the front wall and the rear wall to regulate the thickness of the lower expansion portion when extending and expanding, the tether may constitute a gas flow guide member. The left and right ends of the tether is spaced from the left and right edges of the airbag and arranged in the transverse directions. In this airbag, the gas communication ports are formed between the left and right ends of the tether and the left and right edges of the airbag. Therefore, the inflating gas in the lower expansion portion is guided by the tether to flow from the left and right gas communication ports into the upper expansion portion. The gas flows in the lower expansion portion to the two left and right sides so that the lower expansion portion extends and expands widely leftward and rightward to cover the left and right peripheral edges of the airbag opening.
In the tether thus far described, if the tether arranges a gas communication port near its transverse center for feeding the inflating gas to the upper expansion portion, the expansion of the upper expansion portion can be promoted by the gas communication port near the center.
When an inflator for discharging the inflating gas is arranged in the lower expansion portion of the airbag, the gas flow guide member may be formed in a tubular shape with its two left and right ends opened and covering the inflator.
In this case, if the gas flow guide member has an auxiliary opening at a transverse central portion for feeding the inflating gas to the upper expansion portion, and the expansion of the upper expansion portion can be promoted by the auxiliary opening.
In this case, if the gas flow guide member has narrowed ends and if the auxiliary opening is sewn at its peripheral edge with a sewing thread for allowing the auxiliary opening to open, when thread breaks, the auxiliary opening is not opened from the beginning of the gas inflow. In this airbag, however, after the lower expansion portion is extended and expanded to a certain extent leftward and rightward, the inflating gas is fed from the auxiliary opening to the upper expansion portion because the auxiliary opening opens.
The means for extending and expanding the lower expansion portion widely leftward and rightward may be the folded shape of the airbag. For example, an inflator for discharging the inflating gas is arranged near the transverse center in the lower expansion portion of the airbag, and the airbag includes a wall arranged on the vehicle side upon completion of the extension and expansion, and a wall on the passenger side opposite the vehicle side wall upon completion of the extension and expansion. Also, the airbag is folded vertically so that it is narrowed on the left and on the right. The rear wall is constructed with portions (joined portions) which are joined to the transverse central portion and arranged respectively between the transverse central portion and the left and right edges of the airbag. In this case, means for extending and expanding the lower expansion portion transversely may consist of a fold which the folded portions of the two left and right edges of the airbag are respectively arranged on the side of the front wall portion at the positions of the left and right joined portions of the rear wall, at the vertical folding step.
With this construction, as the folded portions on the two left and right edge sides of the airbag are unfolded, they are directed toward the vehicle away from the joining positions and are unfolded while expanding widely leftward and rightward. Then, the lower expansion portion of the airbag completes its extension and expansion. At the initial stage of the extension and expansion of the airbag, more specifically, the lower expansion portion of the airbag extends and expands widely leftward and rightward from the peripheral edge of the airbag opening.